1. Field of the Invention
The present invention is generally concerned with clutch release bearings, in particular designed to be fitted to automotive vehicles.
2. Description of the Prior Art
As is known, a clutch release bearing generally comprises a drive member, by means of which it is adapted to act on the clutch release device of the clutch it is designed to control, an operating member through the intermediary of which it is adapted to be acted on by a control member, in practice a yoke member commonly referred to as the clutch release yoke, and means coupling together said drive member and said operating member in the axial direction.
The present invention is more particularly directed to clutch release bearings of this kind in which there is provided, in association with the operating member, a generally annular member, referred to hereinafter for convenience as a bush, constrained to move with said operating member in at least one direction, being the axial direction in which said control member is operative, and which has at least one integral radial arm on which said control member acts, and in practice two such arms.
A bush of this kind, in thus providing the arms necessary for the control member to act on, offers the advantage of simplifying the design of the operating member.
Moreover, it may also, if required, itself constitute all or part of the coupling means coupling the drive member to the operating member in the axial direction.
A clutch release bearing equipped with a bush of this kind is described in particular in French Pat. No. 2 090 935 filed Apr. 29, 1971 under the number 71 15343.
In practice, the clutch release bearing described in this French Patent is more particularly intended for fitting to touring vehicles.
Being a clutch release bearing designed to be slidably mounted on a guide member, its operating member is reduced to a sleeve to part of which the associated bush is axially coupled, this bush itself forming the coupling means which couple the corresponding drive member to the operating member in the axial direction, said bush being for this purpose crimped to the latter member.
As a corollary to this, the arms provided by this bush for the control member to act on form part of a flange extending in a generally transverse direction which is substantially flat and on which said control member bears directly.
Such arrangements can prove satisfactory, particularly when fitted to touring vehicles.
They have disadvantages, however, especially in the case of fitting to industrial vehicles.
First of all, to be able to withstand the wear to which it is inevitably subjected in service due to contact with the control member, the bush, which is in practice of metal, must receive appropriate hardening treatment.
Apart from the fact that such hardening treatment, which is in practice a quench treatment, may result in unwanted deformation of the bush, once hardened the bush is not so well suited to subsequent crimping operations.
To permit such crimping, it must be locally annealed, calling for a further operation and so increasing the cost.
Furthermore, to be able to withstand the bending loads to which they are subjected in service by virtue of the axial clutch release load applied to them by the control member, the radial arms of the bush, or in this instance the transverse flange of which they form part, must have sufficient rigidity.
The blank from which the bush is in practice stamped must therefore have a certain thickness, which makes more difficult the stamping operations required to form it and the crimping operations to which it is subsequently subjected, as already mentioned.
In the case of industrial vehicles, in which the axial clutch release load deployed is relatively high, this thickness becomes excessive.
A general object of the present invention is an arrangement by means of which these disadvantages may be overcome and also conferring further advantages.